How use ArduinoDue as ISP, how Use ArduinoDue as Controller

I currently have 2 ArduinoDue and want to use them as a game controller.
so far, these are the information i have gathered are:

  1. The Unojoy project
    according to this project you should upload with the given code to the ATmega16u2 chip, this is done by short circuit the reset and gnd pin, but for the due to which chip should i upload the sketch and how?

  2. this upload to the ATmega16u2 is ( upgrading the firmware....)
    it is quite different with the due board, the upload is done using another board which act as a programmer, then the programmer board is connected to the computer, the ArduinoISP from examples sketch is uploaded to the programmer board. then some PWM pin from the programmer board is connected to the ICSP pin of the board that need to be programmed and use avrdude to upload the hex file to the board

These are the steps i have tried so far but so far i got error message "Please select a programmer from Tools->Programmer menu". help please.

In Arduino IDE, there should be a thing circled in the picture below.